1. Field of the Invention
The present invention relates to an image retrieval system and an image retrieval method in which characteristic values and/or pieces of attribute information are extracted from pieces of image data such as moving images or static images recorded in analog or digital and in which the retrieval of desired image data is performed by using the extracted characteristic values and/or the pieces of extracted attribute information.
2. Description of Related Art
FIG. 1 shows the configuration of a system as an example of a conventional image retrieval processing system. This system is disclosed in a letter “Synthesis and Evaluation of the Image Database with Fully Automated Keyword Extraction by State Transition Model and Scene Description Language” edited by Institute of Electronic Information and Communication Engineers of Japan, D-II Vol. J79-D-II No.4, pp.476-483, April of 1996. In this system, static images are processed in the image retrieval. That is, an area of each of images is divided into a plurality of segments in an area dividing unit 103 of a preparation unit 101, and a plurality of keywords are attached to each divided segment. As the keywords, a conception keyword and a scene description keyword are prepared. In a conception keyword extracting unit 104, a conception keyword 108 of each segment is obtained according to a color and a characteristic value of the segment by using conception keywords respectively allocated to color information in advance. In a scene description keyword describing unit 105, a predicate relating to “position”, “color”, “shape”, “size”, “direction” or the like is obtained from a plurality of image characteristic values of segments. In the unit 105, an operation 106, in which a user 107 selects one predicate from predicates defined in advance and describes the selected predicate, is required, and the selected predicate is output as a scene description keyword 109. In a retrieval tool 102, conception keywords and scene description keywords are prepared in advance. A user 111 selects one conception keyword and one scene description keyword as each of keywords 112 from the prepared keywords. In a characteristic identifying unit 110, an identity of characteristic values is checked by comparing each keyword 112 selected by the user 111 with the conception keyword 108 or the scene description keyword 109 attached to each segment of the image, and an image retrieval processing is performed for the image.
However, in the above-described image retrieval processing system, an identity of characteristic values is checked by using keywords such as conception keywords and scene description keywords selected by the user 112 and keywords attached to each image, and an image retrieval processing is performed according to the characteristic values of each image. Therefore, all images are searched according to only the characteristic values of the images, so that it takes a lot of time to retrieve a desired image.
Also, in the above-described image retrieval processing system, a description method or a storing method of each keyword is not considered. Therefore, it is required that a plurality of image servers relate to a plurality of retrieval tools denoting clients in one-to-one correspondence. As a result, a system, in which many users respectively perform the image retrieval through a network while using various retrieval tools, cannot be provided for the users.
Also, because only static images are processed in the image retrieval, it is difficult to retrieve a desired moving image.